Short-term Effects of Overnight Orthokeratology on Corneal Cell Morphology and Corneal Thickness

Abstract

OK lenses for myopia induce significant structural and optical changes particularly in the central epithelium after 15 days or 1 month of wear. The central corneal epithelium responds to OK wear by undergoing significant epithelial cell shape and size alterations with no effects, however, on the cells of the corneal endothelium or the corneal stroma. Peripheral corneal thickness increased with respect to baseline values. These findings suggest that the corneal epithelium is the principal structure affected by the mechanical forces exerted by the OK lenses.

Short-Term Effects of Overnight Orthokeratology on Corneal Sub-basal Nerve Plexus Morphology and Corneal Sensitivity

“…Nieto-Bona et al 11,13 also noted Positive values shown in the Δ column correspond to a rise in the parameter value.…”

“…However, although its effects on corneal topography, visual acuity, contrast sensitivity, optical quality of the eye, and biomechanical properties have been widely investigated, [5][6][7][8][9][10] only a few studies have examined the histological effects of this technique on the morphology of the human cornea. [11][12][13] In 2011, Nieto-Bona et al 13 published the results of a year-long clinical study including individuals who wore OK lenses daily. This study reported corneal structural and optical changes.…”

Tear Film Osmolarity in Response to Long-Term Orthokeratology Treatment

“…[13][14][15] Some studies have also determined OK effects on tear film components, 16 such as inflammatory mediators. 17 These studies conducted both in animals [18][19][20] and humans 6,7,12 have identified corneal changes produced in stromal and epithelial cell density, SBNP thickness and distribution, 7,12 and epithelial layer thickness ans also changes in the levels and distribution of proinflammatory mediators in the tear film samples of OK wearers. 17,21 To date, however, the effects of OK treatment on tear film osmolarity (TFO ) have not yet been examined.…”

“…5 The success of OK has been accompanied by a need to address the corneal response to treatment. Recent research efforts have examined changes in corneal morphology and physiology by assessing the effects of treatment on cell density, [6][7][8] thicknesses of the corneal layers, [9][10][11] subbasal nerve plexus (SBNP) distribution, 7,12 and corneal biomechanics. [13][14][15] Some studies have also determined OK effects on tear film components, 16 such as inflammatory mediators.…”

Mapping the Corneal Sub-Basal Nerve Plexus in Orthokeratology Lens Wear Using in vivo Laser Scanning Confocal Microscopy

“…Lenses are worn during sleep and removed on waking to temporarily correct refractive error, thereby providing clear, unassisted vision throughout the day. 23 Many studies have shown that OK-induced changes to the corneal contour are the result of changes in the epithelial layer [24][25][26][27] ; however, no studies have investigated the effects of OK treatment on the SBNP. Furthermore, several researchers have suggested that sub-basal nerves and epithelial cells migrate in tandem, 21,[28][29] so an investigation of SBNP changes during OK treatment may increase our understanding of epithelial layer changes during this modality of contact lens wear.…”